Generally, a voltage regulator is a three-pin device, which has an input terminal for inputting power that needs to be stabilized, an output terminal for outputting constant voltage, and a ground terminal, on the outside thereof, and which has a circuit for converting the signal, input through the input terminal, into a stable constant voltage on the inside thereof. Such a voltage regulator has been used in power supply devices of various types of electronic appliances
FIG. 1 is a diagram schematically showing the construction of a conventional voltage regulator including trimming pads and fuses.
As shown in FIG. 1, a conventional voltage regulator 10 includes an analog circuit 1 having an amplifier and a transistor, and a voltage division unit 2 having a resistor layer for metal wires, functioning as a plurality of resistors, trimming pads TP1 to TPn, and a plurality of fuses FUSE1 to FUSEn-1 capable of electrically shorting the trimming pads TP1 to TPn.
That is, in the voltage division unit 2, the trimming pads TP1 to TPn are connected in parallel with respective resistors of the resistor layer to activate selected resistors, thus adjusting the voltage division ratio of the voltage division unit 2. The fuses FUSE1 to FUSEn-1 are formed to be able to electrically short neighboring trimming pads, among the trimming pads TP1 to TPn, to each other.
However, the conventional voltage regulator 10 is problematic in that, in an actual device, the analog circuit 1 and the voltage division unit 2 are arranged in a horizontal space, and the trimming pads TP1 to TPn and the fuses FUSE1 to FUSEn-1 are separately provided in the voltage division unit 2, which is used to determine the output voltage of the voltage regulator 10, so that the size of the chip of the voltage regulator 10 is increased, and thus the manufacturing costs thereof are increased, and the production yield relative to the amount of material is decreased.
Further, the conventional voltage regulator 10 is designed and produced in the state in which all of the resistors of the resistor layer are deactivated by the trimming pads TP1 to TPn and the uncut fuses FUSE1 to FUSEn-1, and is operated such that the trimming pads TP1 to TPn, connected to each other through the fuses FUSE1 to FUSEn-1, are opened by selectively fusing the fuses FUSE1 to FUSEn-1 using high current or a laser during a subsequent testing process, thus enabling the resistors, connected in parallel with the opened trimming pads TP1 to TPn, to be activated, and consequently obtaining a required output voltage.
However, the conventional voltage regulator 10 is problematic in that a trimming process for fusing the fuses connected to the trimming pads must be added, thus raising chip manufacturing costs and increasing a lead time.
In addition, the conventional voltage regulator 10 is also problematic in that, during a trimming process performed using high current or laser, the voltage regulator 10 may be subject to latent damage due to high levels of energy.